This study will test the effectiveness of Heart Rate Variability (HRV) Biofeedback as a therapeutic tool in the reduction of everyday memory problems routinely experienced by combat veterans with Posttraumatic Stress Disorder (PTSD). The study is innovative in three ways: (1) through its investigation of the clinical use of a novel PTSD treatment technology, (2) by focusing on the understudied aspect of the daily functioning of PTSD veterans, and, (3) by investigating a heretofore untested application of biofeedback for PTSD induced deficits in attention (ATTN) and immediate memory (IM). Though HRV Biofeedback has proven successful for several applications in the general population, the idea that deficits in ATTN/IM in combat veterans with PTSD can be remedied by normalization of HRV has not yet been tested empirically. HRV is functionally incorporated into attentional processes, essentially operating as an index of autonomic flexibility and the ability to self-regulate in response to stimulation from the environment. Low HRV occurs in patients with PTSD, General Anxiety Disorder, and Coronary Artery Disease, and is correlated with negative affect and hostility. HRV Biofeedback training has been shown to be effective in increasing HRV in these groups of patients, as well as improving psychological well-being and physiological function in patients with Depression, Fibromyalgia, and Cardiovascular Disease. Therefore, the interrelationship between HRV and ATTN/IM problems in PTSD+ Combat veterans warrants further investigation. If HRV Biofeedback significantly improves ATTN/IM in these subjects, then it can be offered to VA clinicians treating combat PTSD as an effective new treatment tool.